Changes in Concentrations of IAA, ZR and GA₃ during Fruit Development of Parthenocarpic and Self-pollinated Citrus Cultivars

Changes in concentrations of indol-3-acetic acid(IAA),ribosylzeatin(ZR) and gibberellin(GA₃) in different fruit positions of Kamei satsuma mandarin (Citrus unshiu Marc.) and Egan 1 tangerine (C. reticulatau Blanco) fruits were investigated during fruit development. The results indicated that IAA concentrations in the rinds of the two cultivars showed similar trends with obvious peaks at the stage of fruit enlargement, though Egan 1 had the higher value. Opposite change patterns were observed in ZR concentrations between the two cultivars during fruit enlargement, when ZR concentration in Kamei rind was relatively high and increased progressively, whereas that of Egan 1 was declined. GA₃ concentrations of both cultivars presented similar change trend, increasing during fruit enlargement and then decreasing. IAA, ZR and GA₃ concentrations in Kamei pulp, were relatively high at early stage of fruit development. Thereafter, they were reduced conspicuously and remained at low levels. In Egan 1, IAA and GA₃ concentrations were clearly increased during fruit enlargement, which were significantly higher than those of Kamei. ZR concentration in the pulp of Egan 1 decreased, with a trend similar to Kamei, but the former was lower than the latter. IAA,ZR and GA₃ concentrations in the seed of Egan 1 were relatively high at 72 days after full bloom,followed by abrupt decrease to low but constant levels.